People with dementia are experiencing poor care in hospital, according to a national audit.

A team from the Royal College of Psychiatrists says the number of elderly dementia patients who received an assessment in hospital of their mental state or delirium was "alarmingly low". Many get acutely confused when admitted to hospital, but less than half the 7,987 patients in the audit were assessed.

In spite of the growing numbers of elderly people needing treatment, a third of hospitals do not have guidance in place to ensure that the patient's carer is fully informed and involved in decisions.

The audit was commissioned by the Healthcare Quality Improvement Partnership (HQIP) and carried out by a team from the college and other organisations. It looked at data from 210 hospitals across England and Wales and examined the case notes of nearly 8,000 patients.

On the positive side, it found that there had been a 10% drop in the numbers of patients prescribed antipsychotic drugs and patients were more likely to receive an assessment of their nutritional needs.

But 41% of hospitals do not provide training in dementia care for new staff, 40% do not train support staff such as receptionists, and 11% do not train nurses.

George McNamara, head of policy at the Alzheimer's Society, said: "Hospitals are under immense public and political pressure to improve their standards, but given that people with dementia occupy a quarter of hospital beds, it is scandalous that improving dementia care is not a top priority for a number of hospital managers.

"We know that staff want to improve their knowledge of dementia care, but they need to be offered the right tools, support and training to do so. Without a serious culture change to ensure that new policies are actually being put into everyday practice, care for people with dementia cannot and will not improve."

Norman Lamb, the care and support minister, said: "Whilst there are some excellent examples of dementia care in hospitals, this report highlights too many areas where care for patients has failed."

He called on every acute hospital in the country to sign up to the government's call to action on dementia, which includes commitments to making hospitals "dementia friendly" by, for instance, having clear signs to help patients work out where they are and where they need to go.

He said 20 Trusts had so far failed to sign up [see footnote]. They are: Liverpool Heart and Chest NHS Foundation Trust, North Middlesex University Hospital, Northern Devon Healthcare, Northern Lincolnshire and Goole, Papworth, Royal Liverpool, Royal National Hospital For Rheumatic Diseases, Royal National Orthopaedic Hospital, Surrey and Sussex, Rotherham, Derby, Hampshire, Harrogate and District, Hinchingbrooke, Homerton, Kettering, Luton and Dunstable, Nottingham, Royal Brompton and Harefield and West Hertfordshire.

• This footnote was added on 13 July 2013. The Liverpool Heart and Chest and the Northern Lincolnshire and Goole NHS Foundation Trusts are in the process of signing up to the government's call for action on dementia.